Boomvang attaches with line
The boomvang uses a short piece of 1/4" braided dacron line to attach to the mast. I'll attach a photo of mine. I think the length is about 18". I have modified my BoomVang by using a separate camcleat instead of the jam-cleat built into the block, this is not absolutely needed, but it works better for me.There are sources for Owners Manuals for the Evinrude motors, one source is "Ken Cook Co. in Wisconsin, they were stocking various OMC Manuals. You could also try a local Evinrude or Johnson Dealer. Finally, you might get lucky and find a manual for your 4 hp Yachtwin on eBay, an Evinrude or Johnson Manual for the 4hp (not 4-DLX) of the same model year as your motor will be what you need. (Yachtwin really only indicated a longshaft and "sailboat prop" most years)I have a 2001 Johnson 4HP longshaft, basically the same as your Evinrude. It is a good little motor and more than powerfull enough to push a DS. What year is your motor? If it is 1980 or newer, the Model# will tell what year. The Model number should read: E4RLxx where the xx is a 2-letter code. Write out the word "INTRODUCES" and then write 1,2,3,4,5,6,7,8,9,0 underneath. Match the letter code to the number and you find the model year. For instance, if the letters are "CU", then that is a 1987 model (C=8, U=7).